Hi,
Did you manually back up your World, or do you have cloud gaming?
Did you delete the .minecraft folder in AppData, or while uninstalling, did you delete the save files? If so, you have also deleted your save worlds.
If not, please follow the steps below and see if it was backed up in this folder.
- Press Win+R, type %appdata%.minecraft and then click OK.
- Locate .minecraft\saves folder
- You'll see folders for all the Minecraft worlds you've created. Right-click the folder named after the world you want to restore.
- Choose Properties, then go to the Previous Versions tab.
- There, you'll find earlier versions of the world. Just pick one from the list and hit Restore.
Source: How to uninstall Minecraft
Please note that if you do not see the save world, it may be that it was also deleted during installation. Unfortunately, it would be impossible to recover your world. I know how frustrating it is since I also lost my saved world when I reinstalled Minecraft. Since then, I have always backed up my World and saved it on my personal cloud and external device, even though I have cloud gaming.
If you have cloud gaming like Xbox Cloud Gaming, I recommend contacting Xbox support regarding this issue, as Xbox is not a part of this forum. Or contact the developer of your cloud gaming.
If you require further assistance, please don't hesitate to let me know.
Stay Safe!